You will only get a light if they are out of range...if they respond slow or read lower or higher then they should they will not turn on the check engine light.


I would rather know what the oil pressure is then spending money on someone elses jeep.....if you have 10psi it wouldn't rattle but I would pay a lot less for the jeep.

 

Put a mechanical gauge on it to get a true reading. If all is good replace the oil pressure switch.

 

Does your cruise control work? The horn issue could be the clockspring behind the steering wheel.

 

If they respond slow or read lower or higher then they are out of range

 

on the oil pressure issue- this is what mine did whit worn/ovalized cam bearings. no noise. even if i let it run for 20-30 mins with the gauge at "0" it woudlnt rattle or show any signs of anything. just had it rebuild and had to repalced everything. i would keep in the back of your mind it could need an engine when talking about a price. but like already said there is no way to tell without throwing a mechanical gauge on it. i first repalced the sender. then the pump hoping it would take care of it. 3k miles later rebuilt it. $$$$$

the horn and evap leak are very small problems compaired to the oil pressure issue. it sould be feeling like its sttalling from the engine actually siezing intermitantly from lack of lubracation. only seen it 2-3 times but it happens.

why are they selling it?

 

I attached a pic of my evap canister. The black tube should have a hose connected to it. I shot a picture of it when I discovered it was disconnected. Its located under the rear driver side of the jeep just in front of the rear tire. Check that first for your evap leak. The two hoses crack or disconnect easy. I would be willing to bet that is your evap leak issue. Just replace both rubber elbow boots.

As for your oil sending unit. When mine went bad it shot up to 80. I guess it could go bad in the other direction. Its cheap enough to change so try that first.

Check the throttle body for your idle issue. Take it apart and clean it up. Remove the IAC and clean it up. Be careful when messing with it. Just spray it down with throttle body cleaner and wipe it down.

 

The black ball behind the front bumper is not the charcoal canister, that is the vacuum resevoir for the cruise control and HVAC system. Check the oil pressure with a mechanical guage to see if there is a problem, I doubt there is a problem sisnce you hear no abnormal noise.

 

Not in the eyes of the computer, The computer will accept the information comming from the sensors as long as it isn't out of range.

If they respond slow or they give a little higer or lower reading then the true reading the computer has no way of knowing it...the computer accepts the info and adjusts things based on the incorrect reading.

When I say slow what I am talking about is that the computer is always trying to maintain a perfect fuel ratio so it is always a litte rich and them it corrects it and it becomes a little lean so it relys on the O2 sensor to give quick accurate information.

 

Thats a nice looking jeep how much are you going to pay? As for the problem I would check all your wiring starting with the grounds off the battery, When the oil pressure drops do the other gages also drop?

 

The more I read through this thread the more I feel like I would stay clear of this Jeep if I were you. The horn and evap issue are simple enough but poor oil pressure and idle problem could be big. They could be issues together. That engine could be in bad shape. I would probably take it to a mechanic and find out what the problem is. You have not said waht he wants for it but I would guess he wants more than its worth dealing with.

 

tell the seller its the main rod bearing causing no oil pressure, then give him 500.00 for the jeep. Could be as simple as a sensor or something worse.